This invention relates generally to the field of fiber optics, and, more specifically, to plug-receiving adapters which have shielding to restrict access thereto when unmated.
In the optical fiber field, there is a need to connect the optical transmission path of a fiber or device to that of another fiber or device. Often this connection is effected by inserting a plug into an adapter. As used herein, the term xe2x80x9cadapterxe2x80x9d refers to any structure that facilitates fiber/fiber, device/fiber and device/device interconnections. An adapter generally comprises a housing having a port which is configured to receive and hold the housing of a plug to facilitate the plug""s optical connection with another plug or a device connected to the structure. The plug typically comprises a housing which contains a ferrule or other means for holding and precisely positioning one or more fiber ends. When the plug is inserted in the adapter, the adapter and plug are xe2x80x9cmated.xe2x80x9d Likewise, when the plug is not inserted in the adapter, the adapter and plug are xe2x80x9cunmated.xe2x80x9d Specific types of adapters include, for example, connector couplings which facilitate the connection of two plugs. Such couplings may have various configurations (e.g., simplex, duplex and quad) for use in various applications (e.g., backplane and through-chassis interconnections). Another important type of adapter includes those that are attached to or integral with a device to facilitate the optical connection between the plug and the device. Typical devices include, for example, active devices, such as transceivers and transmitters, and passive devices, such as attenuators and multiplexers/demultiplexers.
Although conventional adapters are effective in facilitating connections with plugs, certain problems arise when adapters are connected to a fiber or device on one side but left unmated on the other side thereby leaving their port(s) exposed. One problem in particular is contamination of the fiber or device connected to the unmated adapter. More specifically, if the port is exposed, the fiber or device connected to the adapter may be damaged by adverse environmental hazards such as dust and dirt. Such hazards impair the optical performance of the fiber or device. Another significant problem with an unmated adapter is the emission of dangerous laser light when the device or fiber to which the adapter is connected is xe2x80x9cactivexe2x80x9d and emitting light. Such emissions may pose a significant risk to eyes. Consequently, when an adapter is unmated, it is advantageous to cover its port(s) to prevent dust and other debris from collecting and/or damaging the fiber or device connected to the adapter, and to prevent uncontrolled light emissions.
It is known to provide a dust cover for the adapter port for use during transport or storage or at other times when the adapter is not in use. The use of dust covers, however, presents other problems. For example, such caps may result in light energy being reflected into sensitive optical components causing them damage. More specifically, if an active fiber or device is emitting light along an optical transmission path in an unmated condition, the cap may reflect this light back down the optical transmission path and damage the light-generating component, e.g., a laser, at the other end of the path. Consequently, while an end cap may protect the fiber from dust, dirt and damage from the external environment, it may create perhaps a greater problem by reflecting light energy back into the system.
Another problem with dust covers and end caps is the inconvenience associated with removing them when attempting to mate the adapter with a plug assembly. Furthermore, these covers are misplaced or otherwise not available when the plug assembly is unmated with the adapter, thereby leaving the adapter unprotected and subject to the problems described above.
Problems associated with removable covers were addressed in U.S. Pat. No. 6,004,043 to Abendschein et al. (xe2x80x9cAbendscheinxe2x80x9d), which has the same assignee as the present application. Abendschein discloses a door which is mounted to the adapter housing and is pushed back against the housing wall upon insertion of a plug assembly. Accordingly, the adapter must have adequate room to accommodate the swing radius of the door. However, as industry pressure forces adapters to conform to smaller size limits, it becomes increasingly more difficult to accommodate this swing radius. For example, due to its length, the Abendschein design cannot be used in an adapter which is configured to receive an SC duplex plug.
Therefore, there is a need for a shielded adapter which is convenient and safe to use and which is compact and suitable for miniaturization. The present invention fulfills this need among others.
The present invention provides for a protective adapter that overcomes the aforementioned problems by using opposing shutters in the port rather than a single door or removable cover. The opposing shutters are biased inwardly (i.e., toward the interior of the port) and are configured to meet at an angle when the adapter is unmated. Therefore, when the adapter is unmated, the shutters effectively form a shield to prevent debris from entering the port while preventing laser light from escaping.
The fact that the shutters close at an angle also offers a number of advantages. In particular, any light energy transmitted from a fiber or device coupled to the unmated adapter will be deflected away from the optical transmission path of the fiber or device. This eliminates the risk of light being reflected back down the optical transmission path and damaging the light source. Preferably, the shutters are angled such that they contact the robust housing of the mating plug and pivot away to avoid contact with and/or damage to the plug""s sensitive ferrule.
The use of two shutters also provides for a reduction in adapter size requirements due to the diminished space required to accommodate the swing radius of the shutters. More specifically, since two shutters are used, neither shutter needs to span the entire distance across the port as a single shutter approach requires. This results in shorter shutters having shorter swing radii. By reducing the swing radius of each shutter, the entire adapter can be made smaller.
Accordingly, one aspect of the present invention is an adapter having opposing shutters. In a preferred embodiment, the adapter comprises: (a) a housing having a front and a rear orientation and walls to define a port configured for receiving a mating plug assembly and an opening through the rear of the port, the walls comprising at least two opposing walls; and (b) two shutters, each shutter having a proximate end and a distal end, each shutter being pivotally connected at its proximate end to one of the opposing walls with its distal end extending rearwardly, the shutters being biased inwardly toward the interior of the port such that, when the adapter is unmated, the shutters meet at an angle xcex1 to at least partially shield the opening and, when the adapter is being mated with a plug, the plug contacts the shutters and pivots them outwardly.
Another aspect of the invention is an interconnection system comprising the adapter of the present invention in combination with one or more plugs.
Yet another aspect of the invention is a device comprising the adapter of the present invention.